README: close the buffer since HTTP.jl doesn't do this anymore. (#8)

Author: fredrikekre

README.md

@@ -11,7 +11,8 @@ See the tests for examples, but in a nut shell:
 buff = BufferStream()
 t_processor = @async process(buff)
 HTTP.get(url, response_stream=buff)
+close(buff)
 wait(t_processor)
 ```
 
-You can `readavailable()`, `write()`, `close()`, `eof()`, etc...  The implementation is really simple, so I suggest you just look at it.
+You can `readavailable()`, `write()`, `close()`, `eof()`, etc...  The implementation is really simple, so I suggest you just look at it.